Flamingos and Capybaras have moved into Caroni Swamp: what should we do about it?

This World Habitat Day we’re highlighting how introduced species can reshape habitats, and what this means for how we protect these key ecosystems.

Flamingos in Caroni Swamp, February 2019. L to R Taking off, wading, parent feeding chick. Copyright S. White

Back in 2018, birdwatchers observed flamingo chicks in the Caroni Swamp for the first time. While flamingos had been occasional visitors to the swamp before, this was the first evidence of them actually staying long enough to reproduce. Before this, reports came in of another new resident settling in - capybaras. While the flamingos likely got to the swamp of their own accord, most believe that the capybaras escaped from captivity and started spreading in the wild. The response to these new arrivals has been varied. Most viewed the flamingos as a conservation win. These guys, on the other hand, have received decidedly mixed reviews:

Left, Capybaras caught on camera trap at Caroni, 2015 (courtesy Mike Rutherford & Living World). Right: Capybara babies

While inarguably cute and fluffy, many have seen the introduction of capybaras as a failure of humans to control their captive populations, and some are bracing themselves for the ecological fallout for our native species. The government has gone so far as to declare capybara vermin, and allowed them to be hunted on private land. But is this the right approach? Are capybaras bad for the environment, or is there a silver lining to these new visitors? The answer isn’t simple and gets to the heart of a number of raging debates in animal conservation. But it’s a question worth tackling, as it opens the door to radical new ways of doing conservation. But first:

THE BASICS

Now, before you start thinking we should be flinging exotic pets into the neighbourhood pond to save the planet, we should talk a bit about the devastation that can and has been inflicted when people introduce species to new places. One striking statistic is that the spread of cats and rats by humans around the world accounts for the extinction of at least 163 species globally. There are a couple reasons some introduced species are able to inflict so much damage. One, in a new context, they lack natural predators that keep their numbers in check in their native range. On top of this, native species in their new range are completely naïve to these predators, and are often either preyed upon or outcompeted in their native land. This level of devastation has led ecologists to the “shoot first and ask questions later” approach to introduced species. Meaning that we should always act fast to eliminate exotic species in the wild, just in case they become a threat. This reflects the dominant way of thinking in conservation, and with good reason. However, some now advocate for actively introducing carefully chosen exotic species as a means to actually improve the health of ecosystems, with an approach called re-wilding.

The dreaded lion fish, native to the South Pacific and Indian Oceans, is an example of an exotic species which threatens reef species in the Caribbean.

What is Re-wilding and why should we do it?

In pre-historic times, many large animal species -think wooly mammoths and giant sloths- were abundant across the globe, but were driven to extinction (at least partly) by early humans. Similar losses were seen when European colonizers visited new places for the first time -think dodos, Tasmanian tigers and giant tortoises. The loss of these species impacted ecosystems in a variety of ways, forever changing the landscape of our world. As such many of the ecosystems we see today are unrecognisable from what they would have been before humans arrived on the scene. Re-wilding is the restoration of habitats to their natural, often pre-human state, usually through the reintroduction of large animal species, to replace similar species which have gone (locally or entirely) extinct. The species involved are usually large herbivores or apex predators, which historically played important roles in shaping their ecosystems.

Why do these types of animals have such huge impacts on their ecosystems, you ask? It’s all about how they interact with other species and their physical environment. Large herbivores, for instance, eat large amounts of specific plants, and can entirely change which plants can survive in a given habitat, transforming the landscape. Similarly, predators keep the populations of herbivores in check, with the same impact.

Re-wilding can be a very powerful conservation tool, but has proved controversial with local communities, as it can mean the introduction of animals that residents do not think belong in their areas, and can potentially reshape ecosystems that people are used to. An interesting example is the introduction of giant tortoises to the island, Reunion, in the Indian Ocean. Here, the native tortoises were driven to extinction after colonisation. Without tortoises to graze and disperse certain types of vegetation, the habitat changed dramatically, resulting in a decrease in native plants and an increase in invasive plants, which themselves sustained various bird species. A pilot project introducing different species of giant tortoise to some of these islands, is already helping to restore the original ecosystems, but at the expense of these new habitat types.

Left: What the Mascarene Islands may have looked like before the extinction of its five species of endemic giant tortoises. Right: Aldabra tortoise, one of two species introduced to Round Island to restore its ecosystems.

If you’re thinking “well this sounds like a lot of trouble, let’s just protect them as they are now”, there’s another reason besides nostalgia for re-wilding ecosystems: it may be one of our best tools for saving our ecosystems in an uncertain future.

When we restore ecosystems to their former states, it can give a massive boost to biodiversity, as well as the long-term resilience of ecosystems. A great example of this, is the impact of the 1995 reintroduction of wolves to Yellowstone National Park in the US. Because of their role as apex predators, reintroducing wolves had a range of direct and indirect effects on prey and other predator species, interestingly resulting in the recovery of several species, including bears, eagles, beavers, foxes and antelope {check out this amazing infographic on the subject}.

So we’ve learned about the value of re-wilding, but what does this have to do with the capybaras?

So far, we’ve spoken a bit about how introduced species can often be devastating to ecosystems, and their potential to be really quite good for ecosystems under very specific circumstances. Where do our fluffy friends fit into this? Are we suggesting that we should consider re-wilding Trinidad with capybaras? Unfortunately we don’t have enough evidence to advocate this, but it is something worth dedicating some serious thought and research to. While we couldn’t find robust evidence about whether capybaras were once native to Trinidad before going extinct, biologists speculate that this may very well be the case. Capybaras are present in many South American freshwater habitats, habitats that are very similar to our own. Further, there is evidence that these strong swimmers have occasionally reached our South Western shores where they have been spotted in swamps. On the face of it, the availability of suitable habitats and proximity to the mainland suggest that there is no reason why they should not have lived here at some point in the past.

Does this mean capybaras will restore key ecological processes to our ecosystems? The short answer, again, is we don’t know. As large semi-aquatic herbivores, capybara may alter plant communities through feeding and the transfer of nutrients between the land and aquatic ecosystems. However, we just don’t know enough about their history in Trinidad, their ecosystem impacts or their population growth rates to say for sure what their impact will be. In the face of this, we can understand the precautionary approach of eliminating capybara, however, this could be a lost opportunity. Instead, we are advocating getting to the bottom of these questions through rigorous ecological and paleontological research, before making a decision about the fate of these animals.

A wistful capybara, possibly gazing on to new horizons, or perhaps its fate in Trinidad.

What should we take away from all this?

I guess the real message of this saga is that the best course of action in biodiversity conservation isn’t always obvious, and we should be prepared to challenge conventional ideas about how conservation has to be done. Is our goal to conserve ecosystems exactly as we have always known them? If so, this may be a very difficult task as habitats and species’ geographical ranges will inevitably change due to climate change. Or, should we focus on restoring key processes that will build resilience into ecosystems and allow the most species to survive in an uncertain future? As usually is the case, the answer may be context dependent and we may not come down on one side or the other of this debate. However, the important thing is having the conversation in the first place, being solution-oriented and tackling these issues using the best available evidence- not just going based on our gut reaction. So if you find yourself in an online debate on what we should do about the capybaras in Trinidad, we invite you to pause and think about the evidence before condemning an opposing view- and maybe even find some middle ground.

Thanks to M. Rutherford, G. White and L. Rostant for comments on the history of capybara in Trinidad.